The present invention relates to a flat-panel display device with a reduced thickness and a reduced width of non-displaying peripheral area (referred as xe2x80x9ca picture-frame sizexe2x80x9d).
During late years, flat-panel display devices are widely used in various fields for their advantageous features of thin and light-weight construction, and for low power consumption.
A light-transmission type liquid crystal display for example, comprises a display panel; and an edge-light-type surface illuminant unit for illuminating the display panel. The display panel includes a liquid crystal cell holding a liquid crystal layer between a pair of electrode substrates; and circuitry sections mounted on the electrode substrate, through which circuitry sections a signal driving circuit board and a scanning-line driving circuit board are electrically connected to the electrode substrate.
Conventionally, scanning line driving circuit boards are disposed substantially on the same plane as the liquid crystal substrate, while signal line driving circuit boards are disposed on the thinned section of a wedge-type light guide plate of the surface illuminant unit. The wedge-type light guide plate has a wedge shape in a cross sectional view taken perpendicular to its main surfaces and thus has the thinned section along one edge thereof.
In recent years, there is a demand for maximizing the display screen size or viewing area without changing the overall external size of a liquid crystal module. That is, reduction in the xe2x80x9cpicture-frame sizexe2x80x9d is desired. Accordingly, both the scanning line driving circuit board and the signal line driving circuit board are attempted to be disposed on a reverse side of the light guide plate, that is, on a main surface reverse to a light-emitting main surface of the light guide plate.
Since the above structure allows the placement of the surface illuminant unit and the circuitry section on the back side of the display cell, the structure enables to achieve further reduction in the xe2x80x9cpicture-frame sizexe2x80x9d.
However, in the structure above, while one of the driving circuit boards, for example the signal line driving circuit board, can be disposed on the thinned section of the light guide plate, the other of the driving circuit boards, that is the scanning line driving circuit board have to be placed on the thicker section of the light guide plate, so that a resulted liquid crystal display device would have a large overall thickness.
When a thinner light guide plate is employed to reduce the thickness, the brightness decreases because the amount of light from a tubular light source introduced into the light guide plate decreases. Meanwhile, when electric current is increased to improve the brightness, the power consumption increases. Thus, it has been unable to achieve sufficient reduction in the thickness and the power consumption and improvement in brightness.
The present invention has been made in view of the above technical problems, and aims to provide a flat-panel display device having a reduced picture-frame size and a reduced overall thickness.
According to one aspect of the present invention, a display panel comprises a display panel including a light-transmission type display cell, driving circuits electrically connected to said display cell and control circuit boards electrically connected to said display cell via said driving circuits; a surface illuminant unit including a substantially rectangular light guide plate and a tubular light source disposed on at least one edge surface of said light guide plate, one of its main surfaces of said light guide plate being a light-emitting surface, while said at least one edge surface being light-introducing surface(s); and a bezel holding said display panel interposed between it and said surface illuminant unit; wherein at least one adjacent edge surface adjacent to said light-introducing surface(s) is inwardly inclined to form an acute angle xcex8 relative to said light emitting surface, so that at least a part of said driving circuits or at least a part of said control circuit boards is disposed in a vacancy created by the inclination of said adjacent edge surface.
According to the present invention, the driving circuits or the controlling circuit boards are partially or entirely disposed within the vacancy or recess created by the peculiar shape of the light guide plate, thereby decreasing the thickness of the flat-panel display device.